Compressor

ABSTRACT

A compressor has a hermetic container filled with a lubricant and accommodates an electric element provided with a stator and a rotor and a compressing element, wherein the compressing element includes a shaft, a cylinder block, a piston, a connection mechanism, a bearing, and a thrust ball bearing provided between the rotor and a bearing end surface as an end surface of the bearing, and wherein the thrust ball bearing includes a plurality of balls, a holder portion for holding the balls, upper and lower races disposed on and beneath the balls, a rotation regulation portion for regulating a rotation of the lower race, and a thrust surface provided at the bearing end surface so as to contact with a lower surface of the lower race.

TECHNICAL FIELD

The present invention relates to a compressor used for a freezingdevice, a refrigerating device, and the like.

BACKGROUND ART

In recent years, regarding a compressor used for a freezing device suchas a freezer or a refrigerator, it is required to obtain high efficiencyfor reducing power consumption, low noise, and high reliability.

In the past, this kind of compressor adopts a thrust ball bearing forthe purpose of efficiency improvement so that a shaft is rotatable withrespect to a main bearing (for example, see Patent Document 1).

Hereinafter, a general compressor will be described with reference tothe drawings. FIG. 10 is a longitudinal sectional view showing a generalcompressor disclosed in Patent Document 1. A hermetic container 1accommodates an electric element 2 including a stator 52 and a rotor 54and a compressing element 4 rotationally driven by the electric element2 while being disposed beneath the electric element 2, and a lubricant 6is filled in a bottom portion thereof. The electric element 2 isintegrally formed with the compressing element 4 to form a compressionmechanism 8, and the compression mechanism 8 is elastically supported tothe inside of the hermetic container 1 by a plurality of coil springs(not shown).

A cylindrical compression chamber 22 is formed in a cylinder block 20forming the compressing element 4, and a piston 24 is fitted to theinside of the compression chamber 22 so as to reciprocate. A bearing 26is fixed to the upper portion of the cylinder block 20, and a thrustsurface 28 is formed on the bearing 26.

A shaft 30 includes a main shaft portion 34 axially supported to thebearing 26 in a vertical direction and having a spiral oil-feedinggroove 32 formed in the outer periphery and an eccentric shaft portion36 formed therebelow. The eccentric shaft portion 36 is connected to thepiston 24 via a connection mechanism 44.

Additionally, a pipe-shaped oil filling pipe 42 is press-inserted intoan oil-feeding hole (not shown) formed in a lower end 38 of theeccentric shaft portion 36 so that one end of the oil-feeding pipe 42 iscommunicated from the oil-feeding hole to the spiral oil-feeding groove32.

The electric element 2 includes a stator 52 fixed to the upper portionof the cylinder block 20 and a rotor 54 fixed to the main shaft portion34 of the shaft 30 by shrinkage fitting.

It is assembled so that a center position of a rotor iron core 53 of therotor 54 is substantially identical with that of a stator iron core 51of the stator 52 in a height direction.

Additionally, FIG. 11 is an enlarged view showing a main part of thegeneral compressor. A thrust ball bearing 60 includes a plurality ofballs 62, a holder portion 64 for holding the balls 62, and upper andlower races 66 and 68 disposed on and beneath the balls 62. The upperrace 66 comes into contact with a bore plane 58 in a counter bore 56 asa concave portion of the rotor 54, and the lower race 68 comes intocontact with the thrust surface 28 of the bearing 26. The plurality ofballs 62 roll while coming into contact with the upper race 66 and thelower race 68.

Hereinafter, an operation of the compressor with the above-describedconfiguration will be described.

When a current is supplied from an external power source to the electricelement 2, the rotor 54 rotates. In accompany with the rotation, theshaft 30 rotates, rotation motion of the eccentric shaft 36 istransmitted to the piston 24 via the connection mechanism 44, and thenthe piston 24 reciprocates in the compression chamber 22, therebyenabling the compressing element 4 to perform a predeterminedcompression operation.

Accordingly, a refrigerant gas is sucked from a refrigeration system(not shown) into the compression chamber 22 to be compressed therein,and is again discharged to the refrigeration system.

At this time, the oil-feeding pipe 42 feeds the lubricant 6 by acentrifugal force so as to lubricate each slide movement portion (notshown), and a part of the lubricant is supplied from the spiraloil-feeding groove 32 to the thrust surface 28 so as to lubricate thethrust ball bearing 60.

The weight of the rotor 54 and the shaft 30 is supported by the thrustball bearing 60. Since the ball 62 rolls between the upper race 66 andthe lower race 68 upon rotating the shaft 30, a torque for rotating theshaft 30 becomes smaller than that of a thrust sliding bearing. For thisreason, since it is possible to reduce a loss in the bearing, an inputis reduced, thereby obtaining a high efficiency.

However, in the above-described general configuration example, a slidebetween the ball 62 and the lower race 68 forming the thrust ballbearing 60 or a slide between the lower race 68 and the thrust surface28 of the bearing 26 coming into contact with the lower race 68 maycause an abrasion of the thrust surface 28 of the bearing 26, the ball62, and the lower race 68.

Additionally, the abrasion of the thrust surface 28 of the bearing 26,the ball 62, and the lower race 68 may cause an increase of an input ofthe compressor to thereby deteriorate the efficiency or abrasion powdermay be moved by each slide movement portion together with the lubricant6 to thereby deteriorate the reliability.

[Patent Citation 1]

-   Japanese Patent Unexamined Publication No.Sho61-53474

DISCLOSURE OF INVENTION

According to an aspect of the invention, there is provided a compressorhaving a hermetic container filled with a lubricant and accommodating anelectric element provided with a stator and a rotor and a compressingelement driven by the electric element, wherein the compressing elementincludes a shaft provided with an eccentric shaft portion and a mainshaft portion to which the rotor is fixed, a cylinder block providedwith a compression chamber, a piston reciprocating in the compressionchamber, a connection mechanism connecting the piston to the eccentricshaft portion, a bearing provided at the cylinder block to axiallysupport the main shaft portion, and a thrust ball bearing providedbetween the rotor and a bearing end surface as an end surface of thebearing, and wherein the thrust ball bearing includes a plurality ofballs, a holder portion for holding the balls, upper and lower racesdisposed on and beneath the balls, a rotation regulation portion forregulating a rotation of the lower race, and a thrust surface providedat the bearing end surface so as to contact with a lower surface of thelower race.

In the compressor with the above-described configuration, since therotation of the lower race is prevented at the operation time, it ispossible to prevent an abrasion caused by a slide between the lower raceand the ball or a slide between the lower race and the bearing. Then,since the increase of the input or the abrasion is restricted in acontact portion between the lower race and the ball and a contactportion between the lower race and the bearing, it is possible toprovide a compressor with high efficiency and reliability by restrictingthe increase of the input.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view showing a compressor accordingto a first embodiment of the invention.

FIG. 2 is an enlarged view showing a main part of the compressor.

FIG. 3 is an enlarged view showing a main part of the compressor.

FIG. 4 is a perspective view showing a lower race of the compressor.

FIG. 5 is an enlarged view showing a bearing notch portion of thecompressor.

FIG. 6 is a longitudinal sectional view showing the compressor accordingto a second embodiment of the invention.

FIG. 7 is an enlarged view showing a main part of the compressor.

FIG. 8 is a perspective view showing a lower race of the compressor.

FIG. 9 is an enlarged perspective view showing a bearing end surface ofthe compressor.

FIG. 10 is a longitudinal sectional view showing a general compressor.

FIG. 11 is an enlarged view showing a main part of the compressor.

EXPLANATION OF REFERENCE

101, 201: HERMETIC CONTAINER

102, 202: ELECTRIC ELEMENT

104, 204: COMPRESSING ELEMENT

106, 206: LUBRICANT

120, 220: CYLINDER BLOCK

122, 222: COMPRESSION CHAMBER

124, 224: PISTON

126, 226: BEARING

130, 230: SHAFT

134, 234: MAIN SHAFT PORTION

136, 236: ECCENTRIC SHAFT PORTION

144, 244: CONNECTION MECHANISM

152, 252: STATOR

154, 254: ROTOR

160, 260: THRUST BALL BEARING

162, 262: BALL

164, 264: HOLDER PORTION

166, 266: UPPER RACE

168, 268: LOWER RACE

180, 280: BEARING END SURFACE

182: OUTER PERIPHERAL WALL

184, 284: THRUST SURFACE

186: BEARING NOTCH PORTION

188: PROCESSING TOLERANCE PORTION

190: LOWER-RACE PROTRUSION PORTION

286 a, 286 b, 286 c: BEARING PROTRUSION PORTION

290 a, 290 b, 290 c: LOWER-RACE NOTCH PORTION

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, exemplary embodiments of the invention will be describedwith reference to the accompanying drawings. Additionally, the inventionis not limited to the embodiments.

First Embodiment

FIG. 1 is a longitudinal sectional view showing a compressor accordingto a first embodiment of the invention. A hermetic container 101accommodates an electric element 102 including a stator 152 and a rotor154 and a compressing element 104 rotationally driven by the electricelement 102 while being disposed below the electric element 102, and alubricant 106 is filled in a bottom portion thereof. The electricelement 102 is integrally formed with the compressing element 104 toform a compression mechanism 108, and the compression mechanism 108 iselastically supported to the inside of the hermetic container 101 by aplurality of coil springs (not shown).

The compressing element 104 includes at least a shaft 130, a cylinderblock 120, a piston 124, a connection mechanism 144, a bearing 126, anda thrust ball bearing 160. A cylindrical compression chamber 122 isformed in the cylinder block 120 so that the piston 124 reciprocates inthe compression chamber 122.

The shaft 130 includes a main shaft portion 134 axially supported to thebearing 126 in a vertical direction and having a spiral oil-feedinggroove 132 formed in the outer periphery and an eccentric shaft portion136 formed therebelow. Here, the shaft 130 includes the main shaftportion 134 to which the eccentric shaft portion 136 and the rotor 154are fixed. Additionally, the bearing 126 is provided in the cylinderblock 120 so as to axially support the main shaft portion 134. Theeccentric shaft portion 136 is connected to the piston 124 via theconnection mechanism 144.

Additionally, a pipe-shaped oil-feeding pipe 142 is press-inserted intoan oil-feeding hole (not shown) formed in a lower end 138 of theeccentric shaft portion 136 so that one end of the oil-feeding pipe 142is communicated from the oil-feeding hole to the spiral oil-feedinggroove 132.

The electric element 102 includes the stator 152 fixed to the upperportion of the cylinder block 120 and the rotor 154 fixed to the mainshaft portion 134 of the shaft 130 by shrinkage fitting.

It is assembled so that a center position of a rotor iron core 153 ofthe rotor 154 is substantially identical with that of a stator iron core151 of the stator 152 in a height direction.

FIG. 2 is an enlarged view showing a main part of the compressoraccording to the first embodiment of the invention. A thrust ballbearing 160 is disposed between a thrust surface 184 and a bore plane158 in a counter bore 156 as a concave portion of the rotor 154 in orderto support the self weight of the shaft 130 or the rotor 154. That is,the thrust ball bearing 160 is provided between the rotor 154 and abearing end surface 180 as an end surface of the bearing 126.

The thrust ball bearing 160 includes a plurality of balls 162, a holderportion 164 for holding the balls 162, upper and lower races 166 and 168disposed on and beneath the balls 162, and a rotation regulation portionfor regulating a rotation of the lower race 168. The upper race 166comes into contact with the bore plane 158 of the rotor 154 and thelower surface of the lower race 168 comes into contact with the thrustsurface 184 of the bearing end surface 180.

Each ball 162 is made from bearing steel having a high abrasionresistance property in terms of carbonizing, and a surface hardness isin the range of HRC 60 to 70. Additionally, the upper race 166 and thelower race 168 each has a surface hardness larger than that of analuminum casting forming the bearing 126 or an electromagnetic steelplate forming the rotor 154, and are made from carbon steel having ahigh abrasion resistance property and subjected to a heat treatment.Then, it is manufactured so that a surface hardness is in the range ofHRC 58 to 68 in terms of carbonizing or the like.

Additionally, a rolling surface coming into contact with the ball 162 isnot more than 30 micron in a flatness degree. A surface hardness of theball 162 is set to be slightly larger than that of the upper race 166and the lower race 168.

FIG. 3 is an enlarged view showing a main part of the compressoraccording to the first embodiment of the invention. The bearing 126 isfixed to the upper portion of the cylinder block 120. The bearing endsurface 180 on the bearing 126 is provided with an outer peripheral wall182 formed in the outer periphery of the bearing 126 so as to regulatethe lower race 168 from moving in an outer-peripheral direction and athrust surface 184 coming into contact with the lower surface of thelower race 168. Additionally, the thrust surface 184 is formed in adirection perpendicular to the outer peripheral wall 182.

A height of the outer peripheral wall 182 with respect to the thrustsurface 184 is lower than a plate thickness of the disposed lower race168 and is not less than a half of the plate thickness of the lower race168. A clearance A between an inner diameter of the outer peripheralwall 182 and an outer diameter of the lower race 168 is set to besmaller than a clearance c between an inner diameter of the lower race168 and an outer diameter of the main shaft portion 134.

The lower race 168 is formed so that its lower surface comes intocontact with the thrust surface 184 of the bearing end surface 180.Then, as shown in FIG. 4 as a perspective view showing the lower race ofthe compressor according to the first embodiment of the invention, aplurality of lower-race protrusion portions 190 is provided so as toprotrude outward from the outer peripheral portion of the lower race168. Additionally, the bearing end surface 180 of the bearing 126 isprovided with a bearing notch portion 186 to which the lower-raceprotrusion portions 190 are locked.

FIG. 5 is an enlarged view showing a bearing notch portion of thecompressor according to the first embodiment. The bearing end surface180 is provided with the bearing notch portion 186 so as to penetratethe outer peripheral wall 182 and the thrust surface 184.

The bearing notch portion 186 is formed by processing or die-casting,and is formed on the outer-peripheral side of the bearing end surface180, in which a lubricant fed by the oil-feeding groove 132 cannot flowto the outside, and to be deeper than the thrust surface 184. That is,the bearing notch portion 186 does not communicate with the innerperipheral portion of the bearing 126.

The outer peripheral end of the thrust surface 184 is provided with aprocessing tolerance portion 188 which is formed into an inclinedsurface inclined in a direction away from the thrust surface 184 or aninclined curve-surface shape at the same time when the thrust surface184 is processed. Then, the lower-race protrusion portion 190 and thebearing notch portion 186 form a rotation regulation portion forregulating a rotation of the lower race 168.

Hereinafter, an operation and effect of the compressor with theabove-described configuration will be described.

When a current is supplied from an external power source (not shown) tothe electric element 102 shown in FIG. 1, the rotor 154 rotates.Subsequently, the shaft 130 rotates, rotation motion of the eccentricshaft portion 136 is transmitted to the piston 124 via the connectionmechanism 144, and then the piston 124 reciprocates in the compressionchamber 122, thereby enabling the compressing element 104 to perform apredetermined compression operation.

Accordingly, a refrigerant gas is sucked from a refrigeration system(not shown) into the compression chamber 122 to be compressed therein,and is again discharged to the refrigeration system.

At this time, the oil-feeding pipe 142 feeds the lubricant 106 by acentrifugal force so as to lubricate each slide movement portion, and apart of the lubricant is supplied from the spiral oil-feeding groove 132to the thrust surface 184 so as to lubricate the thrust ball bearing160.

The weight of the rotor 154 and the shaft 130 shown in FIG. 2 issupported by the thrust ball bearing 160. Since the ball 162 rollsbetween the upper race 166 and the lower race 168 upon rotating theshaft 130, a torque for rotating the shaft 130 becomes smaller than thatof a thrust sliding bearing. For this reason, since it is possible toreduce a loss in the bearing 126, an input is reduced, thereby obtaininga high efficiency.

Next, a mechanism for restricting an abrasion, generated between theball 162 and the lower race 168 caused by a slide between the ball 162and the lower race 168, by regulating a rotation of the lower race 168will be described.

It is assembled so that a center position of a rotor iron core 153 issubstantially identical with that of a stator iron core 151 in a heightdirection.

For this reason, the thrust ball bearing 160 and the lower race 168 areapplied with the weight of the shaft 130 and the rotor 154.Additionally, the thrust ball bearing 160 and the lower race 168 areinterposed between the bore plane 158 of the rotor 154 and the thrustsurface 184 of the bearing 126. From this point, since a friction forcegenerated between the lower race 168 and the thrust surface 184 of thebearing 126 becomes larger than that generated between the ball 162 andthe lower race 168, the lower race 168 cannot rotate. As a result, aslide is not generated between the ball 162 and the lower race 168,thereby obtaining a stable rolling of the ball 162.

Additionally, in some cases, it may be assembled such that the centerposition of the rotor iron core 153 is higher than the center positionof the stator iron core 151 due to a non-uniform assembling operation.In this case, an adsorption force generated by the rotor 154, that is, aforce for returning downward the rotor 154 is generated so that themagnetic centers are identical with each other because the magneticcenter of the rotor 154 is deviated upward from that of the stator 152.

Then, the thrust ball bearing 160 and the lower race 168 are appliedwith the weight of the shaft 130 and the rotor 154, and are morestrongly fitted between the bore plane 158 of the rotor 154 and thethrust surface 184 of the bearing 126 in terms of the force forreturning downward the rotor 154. For this reason, since a frictionforce generated between the lower race 168 and the thrust surface 184 ofthe bearing 126 becomes larger than that generated between the ball 162and the lower race 168, the lower race 168 cannot rotate.

As a result, since a slide is not generated between the ball 162 and thelower race 168, it is possible to obtain a stable rolling of the ball162.

Additionally, in a case where it is assembled such that the centerposition of the rotor iron core 153 is lower than that of the statoriron core 151 in a height direction, a magnetic adsorption forcegenerated by the rotor 154, that is, a force for drawing upward therotor 154 is generated so that the magnetic centers are identical witheach other because the magnetic center of the rotor 154 is deviateddownward from that of the stator 152.

Then, to the thrust ball bearing 160 and the lower race 168 are appliedthe weight of the shaft 130 and the rotor 154 and are applied a forcefor drawing upward the rotor 154. When the force for drawing upward therotor 154 is larger than the weight, since the friction force generatedbetween the lower race 168 and the thrust surface 184 of the bearing 126does not become larger than that generated between the ball 162 and thelower race 168 all the time, the lower race 168 may rotate.

As a result, since a slide is generated between the ball 162 and thelower race 168, and a stable rolling of the ball 162 is not obtained, anabrasion is caused by the slide between the ball 162 and the lower race168.

However, in the first embodiment of the invention, the lower surface ofthe lower race 168 comes into contact with the thrust surface 184 of thebearing end surface 180, and the plurality of lower-race protrusionportions 190 is provided so as to protrude outward from the outerperipheral portion of the lower race 168. Likewise, since the rotationregulation portion is formed by the lower-race protrusion portion 190and the bearing notch portion 186 for locking the lower-race protrusionportion 190 provided at the bearing end surface 180, the lower race 168cannot rotate.

As a result, since a slide is not generated between the ball 162 and thelower race 168, a stable rolling of the ball 162 is obtained.Accordingly, since it is possible to restrict an increase of an input oran abrasion, it is possible to provide the compressor with highefficiency and reliability by restricting the increase of the input.

Then, since the lower-race protrusion portion 190 is provided at theouter peripheral portion of the lower race 168, it is possible tobroaden a rolling surface of the lower race 168 on which the ball 162rolls. Accordingly, since the stable rolling of the ball 162 is obtainedand the increase of the input or the abrasion is restricted, it ispossible to obtain the high reliability of the thrust ball bearing 160.

Additionally, in the bearing end surface 180 on the bearing 126, theouter peripheral wall 182 is formed on the outer-peripheral side of thebearing 126 so as to be perpendicular to the thrust surface 184.

Then, the clearance A between the outer diameter of the lower race 168and the inner diameter of the outer peripheral wall 182 is smaller thanthe clearance c between the inner diameter of the lower race 168 and theouter diameter of the main shaft portion 134, the outer peripheralsurface of the lower race 168 comes into contact with the innerperipheral surface of the outer peripheral wall 182 before the lowerrace 168 comes into contact with the main shaft portion 134. That is, interms of the outer peripheral wall 182 surrounding the outside of thelower race 168, the inner peripheral surface of the lower race 168 islocated at a position not coming into contact with the outer peripheralsurface of the rotating main shaft portion 134.

Accordingly, since it is possible to regulate an excessive movement ofthe lower race 168 in a horizontal direction, the lower race 168 cannotdamage the main shaft portion 134 to generate abrasion powder. For thisreason, since it is possible to restrict the increase of the input orthe abrasion, it is possible to provide the compressor with highefficiency and reliability by restricting the increase of the input.

Additionally, the height of the outer peripheral wall 182 formed in thebearing end surface 180 on the bearing 126 is set to be lower than theheight of the lower race 168 and to be not lower than the heightobtained by adding the height of the thrust surface 184 to a half of theplate thickness of the lower race 168.

For this reason, it is possible to prevent a case in which the lowerrace 168 configured to come into contact with the thrust surface 184 ofthe bearing 126 is located on the outer peripheral wall 182 due to avibration generated during a transportation or an operation of thecompressor to be thereby inclined. Additionally, it is possible toprevent the noise or input from increasing due to a contact between theholder portion 164 and the outer peripheral wall 182. Then, since thestable rolling of the ball 162 is obtained and the abrasion or the likeof the ball 162 or the lower race 168 caused by a partial contact of theball 162 is prevented, it is possible to provide the compressor withhigh efficiency and reliability.

Additionally, the bearing notch portion 186 is formed in the bearing endsurface 180 so as to penetrate the outer peripheral wall 182 and thethrust surface 184, and to be deeper than the depth of the thrustsurface 184 of the bearing 126.

For this reason, even when the bearing notch portion 186 is formed, theflatness degree of the thrust surface 184 of the bearing 126 ismaintained and the lower race 168 is prevented from being inclined,thereby obtaining the stable rolling of the ball 162. As a result, sinceit is possible to prevent the increase of the input accompanied by theunstable rolling of the ball 162 or the abrasion or the like of the ball162 and the lower race 168 caused by the partial contact of the ball162, it is possible to provide the compressor with high efficiency andreliability.

Additionally, the lubricant 106 fed to the oil-feeding pipe 142 in termsof a centrifugal force is supplied to the thrust surface 184 via thespiral oil-feeding groove 132 provided in the outer periphery of themain shaft portion 134 so as to lubricate the thrust ball bearing 160.Since the bearing notch portion 186 is formed only on the outerperipheral side of the bearing end surface 180, the inner periphery ofthe bearing 126 does not communicate with the bearing notch portion 186.For this reason, it is possible to prevent a case in which the lubricant106 fed by the oil-feeding groove 132 provided in the shaft 130 flowsfrom the inner periphery of the bearing 126 to the outside of the slidemovement portion via the bearing notch portion 186 without lubricatingthe thrust surface 184.

As a result, since the lubricant 106 is sufficiently supplied to theslide movement portion in the periphery of the thrust ball bearing 160,it is possible to prevent the increase of the input due to theinsufficiency of the lubricant 106 and the abrasion or the like of theball 162 and the lower race 168, and thus to provide the compressor withhigh efficiency and reliability.

Additionally, since the processing tolerance portion 188 is provided inthe outer peripheral end of the thrust surface 184 provided on thebearing end surface 180, a convex portion is removed from the outerperipheral end of the thrust surface 184 of the bearing 126.

As a result, since it is possible to prevent a case in which the lowerrace 168 is located on the convex portion and the lower race 168 isinclined, it is possible to obtain the stable rolling of the ball 162.For this reason, since it is possible to prevent the increase of theinput accompanied by the unstable rolling of the ball 162 and theabrasion or the like of the ball 162 and the lower race 168 caused bythe partial contact of the ball 162, it is possible to provide thecompressor with high efficiency and reliability.

Additionally, in the first embodiment of the invention, an exemplaryembodiment has been described in which the compressing element 104 isdisposed below the electric element 102 and the rotation regulationportion for regulating the rotation of the lower race 168 is provided atthe bearing end surface 180 of the bearing 126 fixed to the upperportion of the cylinder block 120 forming the compressing element 104.However, it is possible to provide the compressor with high efficiencyand reliability with a structure in which the compressing element 104 isdisposed above the electric element 102 and the thrust ball bearing 160is used.

Second Embodiment

FIG. 6 is a longitudinal sectional view showing the compressor accordingto a second embodiment of the invention. A hermetic container 201accommodates an electric element 202 including a stator 252 and a rotor254 and a compressing element 204 rotationally driven by the electricelement 202 while being disposed below the electric element 202, and alubricant 206 is filled in a bottom portion thereof. The electricelement 202 is integrally formed with the compressing element 204 toform a compression mechanism 208, and the compression mechanism 208 iselastically supported to the inside of the hermetic container 201 by aplurality of coil springs (not shown).

The compressing element 204 includes at least a shaft 230, a cylinderblock 220, a piston 224, a connection mechanism 244, a bearing 226, anda thrust ball bearing 260. A cylindrical compression chamber 222 isformed in the cylinder block 220 forming the compressing element 204 sothat the piston 224 reciprocates in the compression chamber 222.

The shaft 230 includes a main shaft portion 234 axially supported to thebearing 226 in a vertical direction and having a spiral oil-feedinggroove 232 formed in the outer periphery and an eccentric shaft portion236 formed therebelow. Here, the shaft 230 includes the main shaftportion 234 to which the eccentric shaft portion 236 and the rotor 254are fixed. Additionally, the bearing 226 is provided in the cylinderblock 220 so as to axially support the main shaft portion 234. Theeccentric shaft portion 236 is connected to the piston 224 via theconnection mechanism 244.

Additionally, a pipe-shaped oil-feeding pipe 242 is press-inserted intoan oil-feeding hole (not shown) formed in a lower end 238 of theeccentric shaft portion 236 so that one end of the oil-feeding pipe 242is communicated from the oil-feeding hole to the spiral oil-feedinggroove 232.

The electric element 202 includes the stator 252 fixed to the upperportion of the cylinder block 220 and the rotor 254 fixed to the mainshaft portion 234 of the shaft 230 by shrinkage fitting.

It is assembled so that a center position of a rotor iron core 253 ofthe rotor 254 is substantially identical with that of a stator iron core251 of the stator 252 in a height direction.

FIG. 7 is an enlarged view showing a main part of the compressoraccording to the second embodiment of the invention. A thrust ballbearing 260 is disposed between a thrust surface 284 and a bore plane258 in a counter bore 256 as a concave portion of the rotor 254 in orderto support the self weight of the shaft 230 or the rotor 254. That is,the thrust ball bearing 260 is provided between the rotor 254 and abearing end surface 280 as an end surface of the bearing 226.

The thrust ball bearing 260 includes a plurality of balls 262, a holderportion 264 for holding the balls 262, upper and lower races 266 and 268disposed on and beneath the balls 262, and a rotation regulation portionfor regulating a rotation of the lower race 268. The upper race 266comes into contact with the bore plane 258 of the rotor 254, and thelower race 268 comes into contact with the thrust surface 284 of thebearing 226.

Each ball 262 is made from carburized bearing steel having a highabrasion resistance property, and a surface hardness is in the range ofHRC 60 to 70. Additionally, the upper race 266 and the lower race 268each has a surface hardness larger than that of an aluminum castingforming the bearing 226 or an electromagnetic steel plate forming therotor 254, and are made from carbon steel having a high abrasionresistance property and subjected to a heat treatment. Then, it ismanufactured so that a surface hardness is in the range of HRC 58 to 68by being subjected to hardening or the like.

Additionally, a rolling surface coming into contact with the ball 262 isnot more than 30 micron in a flatness degree. A surface hardness of theball 262 is set to be slightly larger than that of the upper race 266and the lower race 268.

FIG. 8 is a perspective view showing a lower race of the compressoraccording to the second embodiment of the invention. The lower race 268includes lower-race notch portions 290 a, 290 b, and 290 c.

FIG. 9 is an enlarged perspective view showing a bearing end surface ofthe compressor according to the second embodiment of the invention. Aplurality of bearing protrusion portions 286 a, 286 b, and 286 c areformed in the outer peripheral portion of the bearing end surface 280 onthe bearing 226 in a longitudinal direction of the bearing 226. Thethrust surface 284 is formed in a direction perpendicular to the bearingprotrusion portions 286 a, 286 b, and 286 c extending in a longitudinaldirection of the bearing 226. Herein, the bearing protrusion portions286 a, 286 b, and 286 c regulate the movement of the lower race 268 inan outer peripheral direction.

The bearing protrusion portions 286 a, 286 b, and 286 c are formed atnon-equiangular positions of the bearing 226 in a circumferentialdirection by processing or die-casting. The non-equiangular positionsare defined as P≠Q≠R, where an angle formed between the bearingprotrusion portion 286 a and the bearing protrusion portion 286 b, anangle formed between the bearing protrusion portion 286 b and thebearing protrusion portion 286 c, and an angle formed between thebearing protrusion portion 286 c and the bearing protrusion portion 286a are denoted by P, Q, and R, respectively.

Additionally, the lower race 268 shown in FIG. 8 is installed so thatits lower surface comes into contact with the thrust surface 284 of thebearing end surface 280. Lower-race notch portions 290 a, 290 b, and 290c are provided in the lower race 268 so as to correspond to the bearingprotrusion portions 286 a, 286 b, and 286 c in a circumferentialdirection. Then, the bearing protrusion portions 286 a, 286 b, and 286 cand the lower-race notch portions 290 a, 290 b, and 290 c locked to thebearing protrusion portions 286 a, 286 b, and 286 c form a rotationregulation portion.

Hereinafter, an operation and effect of the compressor with theabove-described configuration will be described.

When a current is supplied from an external power source (not shown) tothe electric element 202 shown in FIG. 6, the rotor 254 rotates.Subsequently, the shaft 230 rotates, rotation motion of the eccentricshaft portion 236 is transmitted to the piston 224 via the connectionmechanism 244, and then the piston 224 reciprocates in the compressionchamber 222, thereby enabling the compressing element 204 to perform apredetermined compression operation.

Accordingly, a refrigerant gas is sucked from a refrigeration system(not shown) into the compression chamber 222 to be compressed therein,and is again discharged to the refrigeration system.

At this time, the oil-feeding pipe 242 feeds the lubricant 206 by acentrifugal force so as to lubricate each slide movement portion, and apart of the lubricant is supplied from the spiral oil-feeding groove 232to the thrust surface 284 so as to lubricate the thrust ball bearing260.

The weight of the rotor 254 and the shaft 230 shown in FIG. 7 issupported by the thrust ball bearing 260. Since the ball 262 rollsbetween the upper race 266 and the lower race 268 upon rotating theshaft 230, a torque for rotating the shaft 230 becomes smaller than thatof a thrust sliding bearing. For this reason, since it is possible toreduce a loss in the bearing 226, an input is reduced, thereby obtaininga high efficiency.

Next, a mechanism for restricting an abrasion, generated between theball 262 and the lower race 268 caused by a slide between the ball 262and the lower race 268, by regulating a rotation of the lower race 268will be described.

It is assembled so that the center position of the rotor iron core 253is substantially identical with that of the stator iron core 251 in aheight direction.

For this reason, to the thrust ball bearing 260 and the lower race 268are applied the weight of the shaft 230 and the rotor 254. Additionally,the thrust ball bearing 260 and the lower race 268 are interposedbetween the bore plane 258 of the rotor 254 and the thrust surface 284of the bearing 226. From this point, since a friction force generatedbetween the lower race 268 and the thrust surface 284 of the bearing 226becomes larger than that generated between the ball 262 and the lowerrace 268, the lower race 268 cannot rotate. As a result, a slide is notgenerated between the ball 262 and the lower race 268, thereby obtaininga stable rolling of the ball 262.

Additionally, in some cases, it may be assembled such that the centerposition of the rotor iron core 253 is higher than the center positionof the stator iron core 251 due to a non-uniform assembling operation.In this case, an magnetic attractive force generated by the rotor 254,that is, a force for returning downward the rotor 254 is generated sothat the magnetic centers are identical with each other because themagnetic center of the rotor 254 is deviated upward from that of thestator 252.

Then, to the thrust ball bearing 260 and the lower race 268 are appliedthe weight of the shaft 230 and the rotor 254, and are more stronglyfitted between the bore plane 258 of the rotor 254 and the thrustsurface 284 of the bearing 226 by the force for returning downward therotor 254. For this reason, since a friction force generated between thelower race 268 and the thrust surface 284 of the bearing 226 becomeslarger than that generated between the ball 262 and the lower race 268,the lower race 268 cannot rotate.

As a result, since a slide is not generated between the ball 262 and thelower race 268, it is possible to obtain a stable rolling of the ball262.

Additionally, in a case where it is assembled such that the centerposition of the rotor iron core 253 is lower than that of the statoriron core 251 in a height direction, a magnetic attractive forcegenerated by the rotor 254, that is, a force for drawing upward therotor 254 is generated so that the magnetic centers are identical witheach other because the magnetic center of the rotor 254 is deviateddownward from that of the stator 252.

Then, to the thrust ball bearing 260 and the lower race 268 are appliedwith the weight of the shaft 230 and the rotor 254 and are applied aforce for drawing upward the rotor 254. When the force for drawingupward the rotor 254 is larger than the weight, since the friction forcegenerated between the lower race 268 and the thrust surface 284 of thebearing 226 does not become larger than that generated between the ball262 and the lower race 268 all the time, the lower race 268 may rotate.

As a result, since a slide is generated between the ball 262 and thelower race 268, and a stable rolling of the ball 262 is not obtained, anabrasion is caused by the slide between the ball 262 and the lower race268.

However, in the second embodiment of the invention, the lower surface ofthe lower race 268 comes into contact with the thrust surface 284 of thebearing end surface 280, and the lower-race notch portions 290 a, 290 b,and 290 c are provided at positions corresponding to the bearingprotrusion portions 286 a, 286 b, and 286 c. Then, since the rotationregulation portion locked to bearing protrusion portions 286 a, 286 b,and 286 c are provided at positions corresponding to the lower-racenotch portions 290 a, 290 b, and 290 c, the lower race 268 cannotrotate.

As a result, since a slide is not generated between the ball 262 and thelower race 268, a stable rolling of the ball 262 is obtained.Accordingly, since it is possible to restrict an increase of an input oran abrasion, it is possible to provide the compressor with highefficiency and reliability by restricting the increase of the input.

Then, since the lower race 268 is provided with the notch portions 290a, 290 b, and 290 c, it is possible to additionally reduce a blankmaterial amount upon punching the lower race 268 using a press, and thusto restrict a material cost of the lower race 268.

Additionally, the bearing protrusion portions 286 a, 286 b, and 286 cand the lower-race notch portions 290 a, 290 b, and 290 c are formed atthe same non-equiangular positions of the bearing 226 and the lower race268 in a circumferential direction, respectively. For this reason, uponcombining the bearing protrusion portions 286 a, 286 b, and 286 c withthe lower-race notch portions 290 a, 290 b, and 290 c, the assemblingoperation needs to be carried out such that one determined surface ofthe lower race 268 is used as a surface necessarily coming into contactwith the ball 262.

As a result, since it is necessary to just ensure a surface roughness ofat least one surface of the lower race 268 coming into contact with theball 262, it is possible to simplify a manufacture process of the lowerrace 268. Accordingly, it is possible to reduce a manufacture cost andto improve productivity.

Additionally, before the lower race 268 contacts with the main shaftportion 234, at least one of the combinations between the lower-racenotch portions 290 a, 290 b, and 290 c and the bearing protrusionportions 286 a, 286 b, and 286 c contacts with each other. That is, interms of the bearing protrusion portions 286 a, 286 b, and 286 c, theinner peripheral surface of the lower race 268 is disposed at a positionnot contacting with the outer peripheral surface of the rotating mainshaft portion 234.

Accordingly, since it is possible to regulate the excessive movement ofthe lower race 268 in a horizontal direction, the lower race 268 cannotdamage the main shaft 234 to generate abrasion powder. For this reason,since it is possible to restrict the increase of the input or theabrasion, it is possible to provide the compressor with high efficiencyand reliability by restricting the increase of the input.

Additionally, in the second embodiment of the invention, an exemplaryembodiment has been described in which the compressing element 204 isdisposed below the electric element 202 and the rotation regulationportion for regulating the rotation of the lower race 268 is provided atthe bearing end surface 280 of the bearing 226 fixed to the upperportion of the cylinder block 220 forming the compressing element 204.However, it is possible to obtain the same advantage with a structure inwhich the compressing element 204 is disposed above the electric element202 and the thrust ball bearing 260 is used.

Additionally, in the first embodiment of the invention, the lower-raceprotrusion portion 190 and the bearing notch portion 186 may be formedat the same non-equiangular positions of the lower race 168 and thebearing 126 in a circumferential direction, respectively. For thisreason, upon combining the lower-race protrusion portion 190 with thebearing notch portion 186, the assembling operation needs to be carriedout such that one determined surface of the lower race 168 is used as asurface necessarily coming into contact with the ball 162.

As a result, since it is necessary to just ensure a surface roughness ofat least one surface of the lower race 168 coming into contact with theball 162, it is possible to simplify a manufacture process of the lowerrace 168. Accordingly, it is possible to reduce a manufacture cost andto improve productivity.

INDUSTRIAL APPLICABILITY

As described above, since the compressor according to the inventionincludes the rotation regulation portion for regulating the rotation ofthe lower race, it is possible to provide the compressor with highefficiency and reliability by restricting the increase of the input,which may be applied to a vending machine, a freezer showcase, adehumidifier, and the like.

1. A compressor comprising: a hermetic container including: a lubricant;an electric element provided with a stator and a rotor; and acompressing element driven by the electric element, wherein thecompressing element includes: a shaft provided with an eccentric shaftportion and a main shaft portion to which the rotor is fixed; a cylinderblock provided with a compression chamber; a piston reciprocating in thecompression chamber; a connection mechanism connecting the piston to theeccentric shaft portion; a bearing provided at the cylinder block toaxially support the main shaft portion; and a thrust ball bearingprovided between the rotor and a bearing end surface as an end surfaceof the bearing, and wherein the thrust ball bearing includes: aplurality of balls; a holder portion for holding the balls; an upperrace and a lower race respectively disposed on and beneath the ball; arotation regulation portion for regulating a rotation of the lower race;and a thrust surface provided at the bearing end surface so as tocontact with a lower surface of the lower race.
 2. The compressoraccording to claim 1, wherein the rotation regulation portion includes;a lower-race protrusion portion protruding outward from an outerperipheral portion of the lower race: and a bearing notch portionprovided at the bearing end surface so as to lock the lower-raceprotrusion portion.
 3. The compressor according to claim 1, wherein therotation regulation portion includes; a bearing protrusion portionprovided at an outer peripheral portion of the bearing end surface; anda lower-race notch portion provided at an outer peripheral portion ofthe lower race so as to lock the bearing protrusion portion.
 4. Thecompressor according to claim 2, wherein the bearing end surface isprovided with an outer peripheral wall regulating a movement of thelower race in an outer peripheral direction.
 5. The compressor accordingto claim 4, wherein a height of the outer peripheral wall with respectto the thrust surface is lower than a plate thickness of the disposedlower race, and is not less than a half of the plate thickness of thelower race.
 6. The compressor according to claim 3, wherein the bearingprotrusion portion provided at the outer peripheral portion of thebearing end surface regulates a movement of the lower race in an outerperipheral direction.
 7. The compressor according to claim 2, whereinthe bearing notch portion is formed deeper than the thrust surface. 8.The compressor according to claim 2, wherein the bearing notch portionis provided at an outer peripheral side of the bearing end surface so asnot to communicate with an inner peripheral portion of the bearing. 9.The compressor according to claim 2, wherein the lower-race protrusionportion and the bearing notch portion are provided at the samenon-equiangular positions of the lower race and the bearing in acircumferential direction, respectively.
 10. The compressor according toclaim 3, wherein the bearing protrusion portion and the lower-race notchportion are provided at the same non-equiangular positions of thebearing and the lower race in a circumferential direction, respectively.11. The compressor according to claim 1, wherein a processing toleranceportion is provided at an outer peripheral end of the thrust surface.